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Using a dual band "rubber duck" like the stock Baofeng antenna and/or the physically longer NA-771, which band will give the best results between two mountain tops given the same input power?

Stereotypically the 2m VHF frequencies are considered to "reach" a little further due to their lower frequency and increased radio horizon. But I'm wondering if a dual-band antenna would actually give higher gain on the 70cm UHF band?

Does a rubber duck achieve a good match on its second harmonic via a trap, i.e. using only half the antenna to radiate on 70cm? In that case maybe both bands end up with a physically short antenna and would probably have similar inefficiencies.

But if some other technique is used perhaps the antenna ends up being less "compromised" on the 70cm band versus the 2m band — either more efficient radiation and/or a better takeoff pattern?

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  • $\begingroup$ My money is on "equally bad in either case" $\endgroup$ – Phil Frost - W8II Mar 10 '17 at 18:16
  • $\begingroup$ Found a teardown showing the inside of a Baofeng stubby: youtu.be/MtnDvWGTKpk?t=144 Looks like the coil has two different pitches, and might actually be shunt fed via a capacitor? $\endgroup$ – natevw - AF7TB Mar 10 '17 at 20:12
  • $\begingroup$ Another name for stubby dual ba(n)d antennas is a poor dummyload. $\endgroup$ – Rowan Hawkins Mar 16 '17 at 2:15
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This is so dependent on the particular antenna, and rubber ducks are such compromise antennas anyway, probably the only way to get a useful answer is to do a shootout between specific antennas.

Pretty much all of the antennas tested by Mike W9MDB here seemed to have higher gain on 2m than 70cm.

I would expect, however, that between similarly sized monoband antennas, a 70cm could have better gain than a 2m, but I don't know if that would make up for 70cm's higher path losses.

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  • $\begingroup$ That is a great link. $\endgroup$ – Rowan Hawkins Mar 16 '17 at 2:23
  • $\begingroup$ Hmm, interesting and fairly relevant link. Seems he's mostly after comparing antennas to each other though. Unfortunately in the fine print of that PDF, it says "UHF dbs9 measurements are not calibrated so can only rely on relative values and not even dB intervals for sure" and unless I missed it also lacks details about the receiver antenna/coax that might be contributing to the 10+ dB difference seen with most. Great starting point at least! $\endgroup$ – natevw - AF7TB Mar 16 '17 at 21:06

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